Alps Electric Co., Ltd.

Junichiro Oya

Tomoyuki Sawataishi

A capacitance-type proximity sensor device includes internal electrodes that are arranged such that capacitance is formed therebetween, external electrodes that are arranged in the outer circumference of the internal electrodes, a driving circuit that outputs a driving voltage, a detecting circuit that detects an output signal, a multiplexer that connects an electrode serving as a driving electrode to the driving circuit, connects an electrode serving as a detecting electrode to the detecting circuit, and connects an electrode serving as a shielding electrode to the ground, and a CPU that calculates the position of an object to be detected. When the object to be detected is detected, the multiplexer changes the internal electrodes and the external electrodes to the detecting electrodes, the driving electrodes, and the shielding electrodes.

Capacitance-type proximity sensor device and electronic apparatus using the same

In a capacitance detecting device including an offset adjustment circuit for removing offset from charge transmitted to an integrator from a charge reading mechanism, the offset adjustment circuit includes a variable capacitance element switching the number of capacitative elements connected in parallel to a charge transmission line made up of a plurality of the capacitative elements and setting the number to a predetermined capacitance value; and a capacitative element for adjustment connected in parallel to the variable capacitance element and parallel, and having a capacitance value corresponding to the minimum value of the capacitative elements constituting the variable capacitance element. Driving is controlled so that offset removal is performed only N times (M&#x3e;N; M and N are natural numbers) in the capacitative element for adjustment while offset removal is repeated M times in the variable capacitance element.

Capacitance detecting device

A capacitance detector includes: a first capacitor with fixed base capacitance and variable capacitance; a second capacitor charged with base charge corresponding to the base capacitance; third and fourth capacitors which receive capacitance distribution from the first or second capacitor; a first switching means for charging the first and second capacitors to a first fixed voltage and charging the third and fourth capacitors to a second fixed voltage in a first section and for charging the first and second capacitors to the second fixed voltage and charging the third and fourth capacitors to the first fixed voltage in a second section; a second switching means for separating the first and second capacitors from the third and fourth capacitors and for connecting the first and second capacitors to the third and fourth capacitors; and a differential amplifier to which first and second voltages corresponding to equalized charge are differentially input.

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Miyagi-ken, Japan

Junichiro Oya